Cleaning blades, cleaning units, electrophotographic imaging apparatuses and electrophotographic cartridges employing the same

ABSTRACT

A cleaning blade to remove a residual toner present on a surface of an electrophotographic photoreceptor, a cleaning unit, an electrophotographic imaging apparatus, and an electrophotographic cartridge including the cleaning blade.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority under 35 U.S.C. §119 from KoreanPatent Application No. 12-2012-0138503, filed on Nov. 30, 2012, in theKorean Intellectual Property Office, the disclosure of which isincorporated herein in its entirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present general inventive concept relates to cleaning blades andcleaning units, electrophotographic imaging apparatuses, andelectrophotographic cartridges employing the cleaning blades. Morespecifically, the present general inventive concept relates to cleaningblades having excellent cleaning performance and durability, cleaningunits, electrophotographic imaging apparatuses and electrophotographiccartridges employing the cleaning blades.

2. Description of the Related Art

Electrophotographic apparatuses used in facsimiles, laser printers,photocopiers and the like produce toned images by using methodsdescribed below, for example. First, a surface of the photosensitivelayer of an electrophotographic photoreceptor is uniformly andelectrostatically charged, and then the charged surface is exposed to apattern of light, thus forming a latent image. The light exposureselectively dissipates the charge in the exposed regions where the lightstrikes the surface, thereby forming a pattern of charged and unchargedregions, which is referred to as a latent image. Thereafter, a toner isprovided in a vicinity of the latent image during development, and thetoner gets charged due to tribocharging by a toner layer regulatingblade made of stainless steel to control a toner layer or injectioncharging. The charged toner then attaches to uncharged regions toproduce a toned image on the surface of the photosensitive layer. Theresulting toned image is electrostatically transferred to a suitablefinal or intermediate receiving surface, such as paper, or thephotosensitive layer may function as a final receptor to receive theimage. Thereafter, the toned image transferred to the final or theintermediate image-receiving surface passes through a fixing process.

Recently, a demand for high quality images with respect toelectrophotography has been rapidly increasing. As a measure forachieving high quality images in electrophotography, a small diametertoner, for example about 5 to about 6 μm, having a shape close to aperfect sphericity (sphericity in a range of about 0.976 to about 0.985when measured by using a flow particle image analyzer (FPIA)) has beenwidely used. Due to the small diameter of the toner, the importance of acleaning technology to remove a residual toner from a photosensitivelayer and to remove external additives and other additives isincreasing. This is because, as the diameter of the toner decreases,cleaning becomes more difficult and may easily lead to a defective imagedue to residual toner remaining on the photosensitive layer aftercleaning.

In order to improve cleaning performances under a low temperature andlow humidity condition (a L/L condition), a conventional cleaning methodgenerally uses a method of controlling properties of the cleaning bladesuch that a peak value of loss tangent, i.e., a peak value of theso-called tan δ, obtained by measuring a dynamic viscoelasticity of thecleaning blade is located in the vicinity of a lowest possibletemperature in which an imaging apparatus having the cleaning blade maybe used. However, a low temperature cleaning performance demanded byconsumers of a cleaning blade is difficult to be satisfied due to adecrease in rubber characteristics and property changes resulting fromstorage at a low temperature and climate conditions experienced duringtransportation of a product. Specifically, storage and operation of acleaning blade in a temperature range of about −5° C. to about 0° C. mayresult in cleaning defects. In particular, according to the conventionalcleaning method, when temperatures representing the peak tan δ value ofany two cleaning blades are assumed to be identical, abrasion resistanceand durability of the cleaning blades may greatly change depending on ashear modulus G* value at that temperature, and, as a result, thecleaning blades prepared to have improved cleaning performances under aL/L condition according to the conventional cleaning method aredisadvantageous in obtaining good high temperature cleaningperformances. Accordingly, the use of a conventional cleaning blade isdifficult to implement in response to a rising demand for highoperational speed and high durability of electrophotographic imagingapparatuses. In a low temperature environment, the conventional cleaningblade has low elasticity, resulting in a poor cleaning performance. Thesame conventional cleaning blade has sufficient elasticity in a hightemperature environment, maintaining efficiency of a cleaningperformance; however, problems such as cracking, poor abrasionresistance and poor durability occur. Specifically, in an L/L condition,a rebound resilience of a polyurethane rubber cleaning blade is highlytemperature dependent and the value thereof decreases as a temperaturedecreases. In this regard, a primary mechanism of the cleaning blade toremove a residual toner under the L/L condition becomes difficult toobtain. Specifically, it becomes difficult for a stick-slip phenomenonof the edge portion of a cleaning blade to occur under the L/Lcondition, decreasing the cleaning performance under the L/L condition.On the contrary, if the rebound resilience of the polyurethane rubbercleaning blade is increased, the cleaning performance improves, but atthe expense of a decreased modulus and a decreased mechanical strengthof the polyurethane rubber. In addition, under a high temperature andhigh humidity condition (a H/H condition), an edge crack may easilyoccur in a polyurethane rubber cleaning blade having a small modulusbecause of an increased coefficient of friction between a photoreceptorsurface and the cleaning blade.

SUMMARY OF THE INVENTION

The present general inventive concept provides cleaning blades havingexcellent cleaning performance in low temperature environments andexcellent abrasion resistance and durability at in high temperatureenvironments.

The present general inventive concept also provides cleaning unitsemploying the cleaning blades.

The present general inventive concept also provides electrophotographicimaging apparatuses employing the cleaning blades.

The present general inventive concept also provides electrophotographiccartridges employing the cleaning blades.

Additional features and utilities of the present general inventiveconcept will be set forth in part in the description which follows and,in part, will be obvious from the description, or may be learned bypractice of the general inventive concept.

Exemplary embodiments of the present general inventive concept provide acleaning blade to remove a residual toner present on a surface of anelectrophotographic photoreceptor, wherein a value of the shear modulusof the cleaning blade over the change in a temperature range of about−5° C. to about 23° C. and a value of the shear modulus at a temperatureof −5° C. of the cleaning blade obtained from a dynamic viscoelasticitymeasurement measured as a function of temperature in a temperature rangeof about −80° C. to about 50° C. under conditions of a frequency of 10Hz, a heating rate of 2.0° C./min, and an initial strain rate of 0.03%satisfy the conditions of 0.292≦ΔG*(MPa)/ΔT(° C.)≦0.490,24.7≦G*(MPa)@−5° C.≦32.4, and wherein ΔG*(MPa)/ΔT(° C.) is a rate of thechange in the shear modulus value G* (unit: MPa) over the change in atemperature range ΔT(° C.) of about −5° C. to about 23° C., andG*(MPa)@−5° C. (unit: MPa) is the shear modulus value at the temperatureof −5° C.

A value of the shear modulus at a temperature of 23° C. furthersatisfies the condition of 9.3≦G*(MPa)@23° C.≦14.6, and whereinG*(MPa)@23° C. is a shear modulus value (unit: MPa) at the temperatureof 23° C.

The cleaning blade may include a polyurethane.

Exemplary embodiments of the present general inventive concept alsoprovide a cleaning unit to remove a residual toner present on a surfaceof an electrophotographic photoreceptor, the unit including a cleaningblade, and a supporting member to support the cleaning blade byattaching to at least one part of the cleaning blade, wherein thecleaning blade removes the residual toner present on the surface of theelectrophotographic photoreceptor, wherein a value of the shear modulusof the cleaning blade over the change in a temperature range of about−5° C. to about 23° C. and a value of the shear modulus at a temperatureof −5° C. of the cleaning blade obtained from a dynamic viscoelasticitymeasurement measured as a function of temperature in a temperature rangeof about −80° C. to about 50° C. under conditions of a frequency of 10Hz, a heating rate of 2.0° C./min, and an initial strain rate of 0.03%satisfy the conditions of 0.292≦ΔG*(MPa)/ΔT(° C.)≦0.490,24.7≦G*(MPa)@−5° C.≦32.4, and wherein ΔG*(MPa)/ΔT(° C.) is a rate of thechange in the shear modulus value G* (unit: MPa) over the change in atemperature range ΔT(° C.) of about −5° C. to about 23° C., andG*(MPa)@−5° C. (unit: MPa) is the shear modulus value at the temperatureof −5° C.

A value of the shear modulus of the cleaning blade at a temperature of23° C. further satisfies the condition of 9.3≦G*(MPa)@23°≦C.≦14.6, andwherein G*(MPa)@23° C. is a shear modulus value (unit: MPa) at thetemperature of 23° C.

The cleaning blade may include a polyurethane.

Exemplary embodiments of the present general inventive concept alsoprovide an electrophotographic imaging apparatus including anelectrophotographic photoreceptor, a charging apparatus to charge theelectrophotographic photoreceptor by contacting the electrophotographicphotoreceptor, an exposure apparatus to form an electrostatic latentimage on a surface of the electrophotographic photoreceptor, adeveloping apparatus to produce a visible image by developing theelectrostatic latent image, a transfer apparatus to transfer the visibleimage onto an image-receiving member, and a cleaning unit to remove aresidual toner present on the surface of the electrophotographicphotoreceptor, wherein the cleaning unit includes a cleaning blade, anda supporting member to support the cleaning blade by attaching to atleast one part of the cleaning blade, wherein the cleaning blade removesthe residual toner present on the surface of the electrophotographicphotoreceptor, wherein a value of the shear modulus of the cleaningblade over the change in a temperature range of about −5° C. to about23° C. and a value of the shear modulus at a temperature of −5° C. ofthe cleaning blade obtained from a dynamic viscoelasticity measurementmeasured as a function of temperature in a temperature range of about−80° C. to about 50° C. under conditions of a frequency of 10 Hz, aheating rate of 2.0° C./min, and an initial strain rate of 0.03% satisfythe conditions of 0.292≦ΔG*(MPa)/ΔT(° C.)≦0.490, 24.7≦G*(MPa)@−5°C.≦32.4, and wherein ΔG*(MPa)/ΔT(° C.) is a rate of the change in theshear modulus value G* (unit: MPa) over the change in a temperaturerange ΔT(° C.) of about −5° C. to about 23° C., and G*(MPa)@−5° C.(unit: MPa) is the shear modulus value at the temperature of −5° C.

A value of the shear modulus of the cleaning blade at a temperature of23° C. further satisfies the condition of 9.3≦G*(MPa)@23° C.≦14.6, andwherein G*(MPa)@23° C. is a shear modulus value (unit: MPa) at thetemperature of 23° C.

The cleaning blade may include a polyurethane.

Exemplary embodiments of the present general inventive concept alsoprovide an electrophotographic cartridge including anelectrophotographic photoreceptor, and a cleaning unit to remove aresidual toner present on a surface of the electrophotographicphotoreceptor after a visible image formed thereon having beentransferred onto an image-receiving member, wherein theelectrophotographic cartridge supports the electrophotographicphotoreceptor and the cleaning unit, and the electrophotographiccartridge is attachable to the electrophotographic imaging apparatus andthe electrophotographic cartridge is detachable from theelectrophotographic imaging apparatus, wherein the cleaning unitincludes a cleaning blade, a supporting member to support the cleaningblade by attaching to at least one part of the cleaning blade, whereinthe cleaning blade removes the residual toner present on the surface ofthe electrophotographic photoreceptor, wherein a value of the shearmodulus of the cleaning blade over the change in a temperature range ofabout −5° C. to about 23° C. and a value of the shear modulus at atemperature of −5° C. of the cleaning blade obtained from a dynamicviscoelasticity measurement measured as a function of temperature in atemperature range of about −80° C. to about 50° C. under conditions of afrequency of 10 Hz, a heating rate of 2.0° C./min, and an initial strainrate of 0.03% satisfy the conditions of 0.292≦ΔG*(MPa)/ΔT(° C.)≦0.490,24.7≦G*(MPa)@−5° C.≦32.4, and wherein ΔG*(MPa)/ΔT(° C.) is a rate of thechange in the shear modulus value G* (unit: MPa) over the change in atemperature range ΔT(° C.) of about −5° C. to about 23° C., andG*(MPa)@−5° C. (unit: MPa) is the shear modulus value at the temperatureof −5° C.

A value of the shear modulus of the cleaning blade at a temperature of23° C. further satisfies the condition of 9.3≦G*(MPa)@23° C.≦14.6, andwherein G*(MPa)@23° C. is a shear modulus value (unit: MPa) at thetemperature of 23° C.

The cleaning blade may include a polyurethane.

The polyurethane may comprise a urethane prepolymer reacted with acuring agent.

The urethane prepolymer may be obtained by reacting a first polyolcompound having two or more hydroxyl groups for each polyol compoundmolecule with an aromatic polyisocyanate compound having two or moreisocyanate groups for each aromatic isocyanate compound molecule.

An equivalence ratio of a hydroxyl group of the first polyol compound toan isocyanate group of the aromatic polyisocyanate compound may be about1:1.1 to about 1:5.

The first polyol compound is at least one of a polyether-based polyol, apolyester-based polyol, and a polyetherester-based polyol, wherein eachof the polyether-based polyol, polyester-based polyol, andpolyetherester-based polyol has 2 to 6 hydroxyl groups and a numberaverage molecular weight of about 1000 to about 8000.

The curing agent may include a second polyol compound having two or morehydroxyl groups for each polyol compound molecule.

The curing agent may further include a multifunctional chain extenderhaving two or more of hydroxyl group, amino group, or a combination ofthese for each multifunctional chain extender molecule, a catalystcapable of catalyzing an addition reaction between an isocyanate endgroup of the urethane prepolymer compound and a hydroxyl group of thesecond polyol compound, and a plasticizer.

An equivalence ratio of the isocyanate groups of the urethane prepolymerto a sum of the hydroxyl group of the second polyol compound in thecuring agent and the functional groups of the multifunctional chainextender may be about 1:0.5 to about 1:5.0.

Exemplary embodiments of the present general inventive concept alsoprovide a cleaning unit to remove a residual toner from a surface of anelectrophotographic photoreceptor, the cleaning unit including acleaning blade, wherein a rate of the change in a shear modulus value G*of the cleaning blade in MPa over a temperature range of about −5° C. toabout 23° C. is between 0.292 and 0.490, and wherein the shear modulusof the cleaning blade at a temperature of −5° C. is between 24.7 MPa and32.4 MPa.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other features and utilities of the present generalinventive concept will become apparent and more readily appreciated fromthe following description of the embodiments, taken in conjunction withthe accompanying drawings of which:

FIG. 1 is a schematic cross-sectional view illustrating a cleaning unitincluding a cleaning blade according to an exemplary embodiment of thepresent general inventive concept; and

FIG. 2 is a schematic cross-sectional view illustrating anelectrophotographic imaging apparatus and an electrophotographiccartridge including a cleaning unit according to an embodiment of thepresent general inventive concept.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the embodiments of the presentgeneral inventive concept, examples of which are illustrated in theaccompanying drawings, wherein like reference numerals refer to the likeelements throughout. The embodiments are described below in order toexplain the present general inventive concept while referring to thefigures.

Hereinafter, an electrophotographic cartridge and an electrophotographicimaging apparatus including a cleaning unit, and a cleaning unitincluding a cleaning blade according to exemplary embodiments of thepresent general inventive concept are described more fully.

FIG. 1 is a schematic cross-sectional view illustrating a cleaning unit21 including a cleaning blade 3 according to an exemplary embodiment ofthe present general inventive concept.

In reference to FIG. 1, the cleaning unit 21 includes a cleaning blade 3removing toner and other residues remaining on a surface of anelectrophotographic photoreceptor 11 after an image having beentransferred and a supporting member 4 supporting the cleaning blade 3 byattaching to at least a part of the cleaning blade 3. A part of thecleaning blade 3 not attached to the supporting member 4 is called afree length of the cleaning blade 3. The toner may be, for example, astyrene-acrylate-based toner or a polyester-based toner. The supportingmember 4 is used to support the cleaning blade 3 and may be fixed on awaste toner collector (not illustrated) located at a bottom of thecleaning unit 21 or fixed on a main body (not illustrated) of anelectrophotographic imaging apparatus 31 (illustrated in FIG. 2,discussed below). The supporting member 4 may be manufactured using, forexample, stainless steel.

The cleaning blade 3 in the cleaning unit 21 applies a blade pressure Non the surface of the electrophotographic photoreceptor 11 and scrapesresidues such as residual toner to remove the residues remaining on theelectrophotographic photoreceptor 11. Cleaning performance of thecleaning blade 3 may be obtained by increasing the blade pressure N orincreasing a cleaning angle θ. However, when the blade pressure isincreased, the electrophotographic photoreceptor 11 wears out morequickly and, as a result, a lifespan of the electrophotographicphotoreceptor 11 decreases. Accordingly, in consideration of the aboveproperties, the cleaning performance may be maintained by decreasing theblade pressure N while increasing the cleaning angle θ. However, careshould be taken because if the cleaning angle θ is too large, thecleaning blade 3 may get rolled up in a rotating direction A of theelectrophotographic photoreceptor 11.

The cleaning blade 3 is generally manufactured using a polyurethane. Apolyurethane cleaning blade has an advantage of cheap material cost.However, an elasticity of the polyurethane abruptly decreases in a lowtemperature environment and, as a result, the cleaning performance ofthe cleaning blade 3 may abruptly decrease in a low temperatureenvironment having a temperature range of about 10° C. to about 20° C.and in a cryogenic environment having a temperature range of about −5°C. to about 0° C. Also, the polyurethane cleaning blade has a sufficientelasticity in a high temperature environment having a temperature rangegreater than about 20° C., which may lead to an excellent cleaningperformance but a poor abrasion resistance and a poor durability, easilyresulting in cracks. Specifically, in a high temperature and highhumidity environment, rebound resilience of the polyurethane cleaningblade becomes too large during a stick-slip movement such that arestoring force with respect to a rubber strain increases, resulting incracks and poor cleaning performance.

However, instead of controlling properties of the polyurethane cleaningblade based on tan δ peak value, if the properties of the polyurethanecleaning blade are controlled based on a shear modulus G* value at aspecific temperature and a value of the rate of change in the shearmodulus G* in MPa over a temperature range ΔT in ° C. (ΔG*(MPa)/ΔT(°C.)) in a specific temperature range, a cleaning blade 3 havingexcellent cleaning performance in a low temperature environment andexcellent abrasion resistance and durability in a high temperatureenvironment may be obtained, resolving problems of the cleaning blademanufactured using a conventional technology.

Shear modulus G* is defined as a square root of a sum of a square ofstorage modulus(G′) and a square of loss modulus (G″), as is well knownto a person having ordinary skill in the art: G*=(G′²+G″²)^(1/2).

Hence, the cleaning blade 3 according to an exemplary embodiment of thepresent general inventive concept is controlled such that itsΔG*(MPa)/ΔT(° C.) value and its shear modulus value at a temperature of−5° C. obtained from a dynamic viscoelasticity measurement measured as afunction of temperature in a temperature range of about −80° C. to about50° C. under conditions of a frequency of 10 Hz, a heating rate of 2.0°C./min, and an initial strain rate of 0.03% satisfy the followingconditions (1) and (2): (1) 0.292≦ΔG*(MPa)/ΔT(° C.)≦0.490, (2)24.7≦G*(MPa)@−5° C.≦32.4, wherein ΔG*(MPa)/ΔT(° C.) is a rate of thechange in a shear modulus value G* (unit: MPa) over the change in atemperature range ΔT(° C.) of about −5° C. to about 23° C., andG*(MPa)@−5° C. (unit: MPa) is a shear modulus value at the temperatureof −5° C.

If the ΔG*(MPa)/T(° C.) value is less than 0.292, cleaning performancein the low temperature and low humidity environment is good becauseelasticity is good; however, the abrasion resistance and the durabilityof the cleaning blade 3 is poor in the high temperature and the highhumidity environment, increasing the possibility of cracks in thecleaning blade 3. If the ΔG*(MPa)/ΔT(° C.) value is greater than 0.490,the abrasion resistance and the durability of the cleaning blade 3 ishigh, decreasing the possibility of cracks in the cleaning blade 3 inthe high temperature and high humidity environment; however, thecleaning performance in the low temperature and low humidity conditionmay be poor because of poor elasticity. If the G*(MPa)@−5° C. value isless than 24.7, the abrasion resistance and the durability of thecleaning blade 3 in the high temperature and high humidity environmentmay be poor. If the G*(MPa)@−5° C. value is greater than 32.4, then thecleaning performance of the cleaning blade 3 in the low temperature andlow humidity environment may be poor. If the cleaning performance of thecleaning blade 3 is poor, the residual toner attaches to a chargingroller 13 (illustrated in FIG. 2, discussed below), contaminating thecharging roller 13. As a result, a charging property of contaminatedsurface areas of the charging roller 13 decreases, resulting in a poorimaging quality due to streaks in areas of the printed imagecorresponding to the contaminated surface areas where the chargingproperty has decreased.

According to another exemplary embodiment of the present generalinventive concept, a shear modulus of the cleaning blade 3 at atemperature of 23° C. may further satisfy the condition (3): (3)9.3≦G*(MPa)@ 23° C.≦14.6, wherein G*(MPa)@23° C. is a shear modulusvalue (unit: MPa) at the temperature of 23° C.

If the G*(MPa)@23° C. value is less than 9.3, the abrasion resistanceand the durability of the cleaning blade 3 may be poor in the hightemperature and high humidity environment. If this value is greater than14.6, cleaning performance may be poor in the low temperature and lowhumidity environment.

To sum up, the polyurethane cleaning blade 3 satisfying all of theconditions (1), (2), and (3) according to an exemplary embodiment of thepresent general inventive concept has excellent cleaning performance,abrasion resistance and durability when imaging in a cryogenicenvironment having a temperature range of about −5° C. to about 0° C. aswell as in a high temperature and high humidity environment having atemperature range greater than about 20° C. Hence, according to anexemplary embodiment of the present general inventive concept, acleaning blade 3 having an excellent cleaning performance in the lowtemperature and low humidity environment and having an excellentabrasion resistance in the high temperature and high humidityenvironment may be obtained by preparing the cleaning blade 3 based onG* (shear modulus) design of the polyurethane cleaning blade.

The cleaning blade 3 is prepared by primarily using a polyurethanerubber or a polyurethane elastomer. According to an exemplary embodimentof the present general inventive concept, the cleaning blade 3 isessentially composed of a polyurethane rubber or a polyurethaneelastomer.

The polyurethane rubber or the polyurethane elastomer may be obtained bypreparing a urethane prepolymer and further reacting the urethaneprepolymer with a curing agent.

The urethane prepolymer may be obtained, for example, by reacting afirst polyol compound having two or more hydroxyl groups for each polyolcompound molecule with an aromatic polyisocyanate compound having two ormore isocyanate groups, preferably between two to four or more andpreferably between two to three isocyanate groups for each aromaticisocyanate compound molecule. The urethane prepolymer may be prepared,for example, by reacting the first polyol compound and the aromaticpolyisocyanate compound, wherein an equivalence ratio of a hydroxylgroup of the first polyol compound to an isocyanate group of thearomatic polyisocyanate compound is about 1:1.1 to about 1:5. If theequivalence ratio is less than about 1:1.1, then there may be a problemthat the end groups of the urethane prepolymer may be a hydroxyl group,not an isocyanate group, and if the equivalence ratio is greater than1:5, then there is difficulty in increasing a molecular weight of theurethane prepolymer.

In regards to preparing the urethane prepolymer, a polyether-basedpolyol, a polyester-based polyol, a polyetherester-based polyol, or amixture of these may be used as the first polyol compound, each of whichhaving preferably 2 to 6, more preferably 2 to 5 hydroxyl groups andhaving a number average molecular weight of about 1,000 to about 8,000.For example, the first polyol compound may be polyether-based polyols,such as polyethylene glycols, polypropylene glycols, polybutyleneglycols, and the like, which can be obtained by additionallypolymerizing ethylene oxide, propylene oxide, THF (tetrahydrofuran) andthe like by, as initiators, using an alcohol compound preferably havingtwo to six, preferably having two to five hydroxyl groups, such asethylene glycol, glycerol, butanediols, trimethylolpropanes,pentaerythritols, and the like. Furthermore, acrylic-modified polyols,silicone-modified polyols, and the like may be used.

In regards to preparing the urethane prepolymer, usable aromaticpolyisocyanate compounds include toluene diisocyanate (TDI),4,4′-methylene diphenyl diisocyanate (MDI), xylene diisocyanate (XDI),isophorone diisocyanate (IPDI), polymethylene polyphenyl polyisocyanate,and the like. Furthermore, a combination of these or modified productsof these may be used. Also, aliphatic diisocyanates such ashexamethylene diisocyanate (HDI) and the like may be used.

If the urethane prepolymers are further reacted with the curing agent,the polyurethane rubbers or the polyurethane elastomers may be obtained.

The curing agent includes a second polyol compound having two or morehydroxyl groups for each polyol compound molecule. The second polyol maybe identical to the first polyol. The curing agent may further include amultifunctional chain extender having two or more of hydroxyl group,amino group, or a combination of these for each multifunctional chainextender molecule, a catalyst capable of catalyzing an addition reactionbetween an isocyanate end group of the urethane prepolymer compound anda hydroxyl group of the second polyol compound, and a plasticizer.

The second polyol compound used in the curing agent may be the same asthe first polyol compound used in preparing the polyurethaneprepolymers.

A preferable equivalence ratio of the isocyanate groups of the urethaneprepolymers to a sum of the hydroxyl group of the second polyol compoundin the curing agent and the functional groups of the multifunctionalchain extender may be about 1:0.5 to about 1:5.0. If the equivalenceratio is less than 0.5, then there is a problem of an insufficientcuring of polyurethane, and if the equivalence ratio is greater than5.0, then the hardness of the polyurethane may increase.

As the chain extender, water, a multifunctional alcohol having a lowmolecular weight such as ethylene glycol, 1,2-propanediol,1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol,glycerol, trimethylpropane, and the like and/or a multifunctionalpolyamine compound such as hydrazine, ethylene diamine, propylenediamine, tetramethylene diamine, pentamethylene diamine, hexamethylenediamine, 1,2-dimethylethylene diamine, 2-methylpentamethylene diamine,diethylenetoluene diamine, 4,4′-diaminodiphenyl ether,2,3-diaminotoluene, 2,4- or 4,4′-diaminodiphenylmethane, 1,3- or1,4-diphenyldiamine, naphthalene-1,5-diamine,1,3-dimethyl-2,4-diaminobenzene, 1,3,5-triethyl-2,4-diaminobenzene,3,3′,5,5′-tetramethyl-4,4′-diaminodiphenylmethane,3,3′-dimethyl-4,4′-diaminodiphenylmethane,3,3′-dichloro-4,4′-diaminodiphenylmethane,4,4′-(1,3-phenyleneisopropylidene)bisaniline,4,4′-(1,4-phenyleneisopropylidene)bisaniline, and the like may be used,and these may be used alone or in combination of two or more. The amountof the chain extender may be about 0.5 wt % to about 10 wt %,specifically between about 1 wt % to about 5 wt % based on the totalweight of the reactants in view of control of a molecular weight of thepolyurethane.

As a curing catalyst catalyzing the addition reaction, tin acetate,dibutyl tin acetate, dibutyl tin dilaurate, dioctyl tin dilaurate,tetrabutyl titanate, dibutyl tin maleate, stannous octoate, leadoctoate, N,N,N′,N′-tetramethyl-1,3-butanediamine, and the like may beused, and these may be used alone or in combination of two or more. Theamount of the catalyst used may be about 0.05 wt % to about 5 wt %,specifically about 1 wt % to about 3 wt % based on the total weight ofthe reactants in view of workability and curing velocity of the curingcatalyst.

When reacting the urethane prepolymer with the curing agent, an acid maybe used to control a reaction rate by controlling a pH of the reactionsystem. When mixing the urethane prepolymer and the curing agent, pH maybe controlled such that the pH is in a range of about 4 to about 6.5. Ifthe pH is less than 4 or greater than 6.5, the reaction rate may slowdown.

As the plasticizer, phthalates such as dibutyl phthalate and dioctylphthalate, and the like; adipates such as dibutyl adipate and dioctyladipate and the like; and octoates may be used alone or in combinationof two or more. The amount of the plasticizer used may be about 1 wt %to about 10 wt % based on the total weight of the reactants. If theamount of the plasticizer exceeds 10 wt %, durability of thepolyurethane may decrease abruptly because of poor mechanical propertyof the polyurethane.

The cleaning unit according to an exemplary embodiment of the presentgeneral inventive concept may integrate into an electrophotographiccartridge 29 or electrophotographic imaging apparatuses 31 (illustratedin FIG. 2, discussed below) such as laser printers, photocopiers,facsimiles, and the like.

FIG. 2 is a schematic cross-sectional view showing anelectrophotographic imaging apparatus 31 and an electrophotographiccartridge 29 including the cleaning unit 21 according to an exemplaryembodiment of the present general inventive concept.

The electrophotographic imaging apparatus 31 according to an exemplaryembodiment of the present general inventive concept includes anelectrophotographic photoreceptor 11; a charging apparatus such as acharging roller 13 charging the electrophotographic photoreceptor 11 bycontacting the electrophotographic photoreceptor 1; an exposureapparatus (not illustrated) forming an electrostatic latent image on asurface of the electrophotographic photoreceptor 11; a developingapparatus 15 producing a visible image by developing the electrostaticlatent image; a transfer apparatus such as a transfer roller 17transferring the visible image onto an image-receiving member; and acleaning unit 21 removing a residual toner present on the surface of theelectrophotographic photoreceptor 11, wherein the cleaning unit 21includes the cleaning blade 3 according to an exemplary embodiment ofthe present general inventive concept, described above with reference toFIG. 1.

The electrophotographic cartridge 29 includes the electrophotographicphotoreceptor 11 and the cleaning unit 21 removing a residual tonerpresent on a surface of the electrophotographic photoreceptor 11 after avisible image formed thereon having been transferred onto animage-receiving member, wherein the electrophotographic cartridge 29supports the electrophotographic photoreceptor 11 and the cleaning unit21 and is attachable to and detachable from an electrophotographicimaging apparatus 31.

With reference to FIG. 2, an electrophotographic photoreceptor 11 in theform of a drum is charged by a charging roller 13 contacting theelectrophotographic photoreceptor 11. Thereafter, the electrostaticlatent image is formed by exposing a laser light (not illustrated) toimage portions. Using a developing apparatus 15, the electrostaticlatent image is changed into a visible image, for example, to a tonedimage and the toned image is transferred to an image-receiving member 19using a transfer roller 17. After the transferring, a residual tonerleft on a surface of the electrophotographic photoreceptor 11 is removedby a cleaning unit 21, specifically by the cleaning blade 3 according tothe exemplary embodiment of the present general inventive conceptdescribed above in reference to FIG. 1. The electrophotographicphotoreceptor 11 can be provided to be used again to form an image inthe next cycle. The developing apparatus 15 includes a toner layerregulating blade 23, a developing roller 25, a toner supplying roller27, and the like.

The electrophotographic cartridge 29 may integrally support theelectrophotographic photoreceptor 11 and, if needed, the chargingapparatus 13, the developing apparatus 15, and the cleaning unit 21according to an exemplary embodiment of the present general inventiveconcept.

Hereinafter, the present general inventive concept will be described ingreater detail according to exemplary embodiments. It should beunderstood that the exemplary embodiments described herein should beconsidered in a descriptive sense only and not for purposes oflimitation.

Examples 1 to 3 (E 1 to 3) and Comparative Examples 1 to 6 (CE 1 to 6)

Mixtures were obtained by weighing and homogenously mixing urethaneprepolymers, which are a main component, and curing agents as shown inTable 1 below, and bubbles formed in the mixtures were removed. Eachmixture obtained was immediately inserted into a mold (not illustrated)using centrifugal casting to prepare a cleaning blade and then cured byheating it to a temperature of 150° C. for about 30 minutes to about 45minutes. A cleaning blade 3 according to an exemplary embodiment of thepresent general inventive concept or a cleaning blade according to aconventional technology was obtained by taking out a polyurethane rubbercleaning blade from the mold.

TABLE 1 Urethane prepolymer main component Curing agent PolyethyleneAmine Ethylene glycol adipate 1,4- Trimethylol curing adipate (Mn =2,000) NCO %*** Of butanediol propane agent* mixing amount mixing amountthe main (parts by (parts by (parts by (parts by weight) (parts byweight) component weight) weight) weight) E 1 100 67 10.9% 7.85 4.75 — E2 100 73 13.7% 6.74 4.12 — E 3 100 79 16.9% 6.52 3.95 trace** CE 1 10062 13.7% 6.91 4.15 — CE 2 100 55 13.7% 5.44 3.31 — CE 3 100 50 13.7%5.03 3.03 trace CE 4 100 82 16.4% 8.42 5.14 — CE 5 100 79 14.5% 8.365.06 — CE 6 100 76 11.7% 7.78 4.88 trace*N,N,N′,N′-tetramethyl-1,3-butanediamine, **less than 300 wt ppm basedon the total polyurethane weight, ***isocyanate group % present at endgroups of the obtained urethane prepolymer assuming that the totalweight of the main component (ethylene adipate + polyethylene adipate +4,4′-methylene diphenyl diisocyanate) is 100Cleaning Performance Test

The printer sets employing each of the cleaning blades obtained inExamples 1 to 3 and Comparative Examples 1 to 6 and developingapparatuses were maintained for more than 24 hours in a Climatic Chambercapable of controlling the temperature of the Climatic Chamber to −5° C.Thereafter, confirmation was made to ensure that the temperature of theClimatic Chamber was below −5° C. and cleaning performancescorresponding to changing environments were tested as follows under theconditions wherein printer processing speed was at about 108 mm/s toabout 343 mm/s (color 4 ppm to 24 ppm), a free length of the cleaningblade of an electrophotographic photoreceptor drum was 7.8 mm, and athickness of the cleaning blade was 2 mm. First, printer sets weremaintained for more than 24 hours and then test images were printed toevaluate printing quality using the printer sets. The printed materialswere used to evaluate cleaning performance of the cleaning blade asdescribed below.

⊚: Vertical black streaks do not occur in non-image areas of the printedmaterials.

∘: If non-image areas are closely analyzed, vertical black streaks arevisible; however, after a continuous printing, the black streaksdisappear.

x: At least one vertical black streak appears clearly in non-image areasof the printed materials.

If at least one clear vertical black streak appears in the non-imageareas of the printed materials, a surface of a charging roller of theprinter set is contaminated.

Abrasion Resistance Test

The printer sets employing each of the cleaning blades obtained inExamples 1 to 3 and Comparative Examples 1 to 6 and developingapparatuses were maintained for more than 24 hours in a Climatic Chambercapable of controlling temperature and humidity to a high temperatureand high humidity (H/H) environment (30° C./85% RH). Thereafter,confirmation was made to ensure that the temperature/humidity of theClimatic Chamber was at 30° C./85% RH, and an abrasion resistancecorresponding to changing environments was tested as follows under theconditions wherein printer processing speed was at about 108 mm/s toabout 343 mm/s (color 4 ppm to 24 ppm), a free length of the cleaningblade of an electrophotographic photoreceptor drum was 7.8 mm, and athickness of the cleaning blade was 2 mm.

First, the printer sets were maintained for over 24 hours. One page wasthen printed by using the printer sets under a user environment having asmall toner consumption (text printing, 1% coverage), followed bypausing an imaging unit for 37 seconds. The processes of printing a pageand pausing the imaging unit were then repeated.

Herein, the abrasion resistance of the cleaning blade was evaluated bycounting a number of printed pages without vertical black streaks innon-image areas. As a number of the high quality printed pagesincreases, print processing time until cracks occur in an edge area ofthe cleaning blade increases, achieving a long lifespan of the printerset.

Response Factor Test

Rheological properties of ΔG*(MPa)/ΔT(° C.) which is a rate of thechange in a shear modulus value G* over the change in a temperaturerange ΔT(° C.) of about −5° C. to about 23° C., G*(MPa)@−5° C. which isa shear modulus value at the temperature of −5° C., and G*(MPa)@23° C.which is a shear modulus value at the temperature of 23° C. of acleaning blade obtained in Examples 1 to 3 and Comparative Examples 1 to6 were measured according to a sine wave oscillation method by using anARES measuring tool provided with a dynamic mechanical analyzer (DMA)manufactured from the Rheometric Scientific, Inc. under the measuringconditions indicated below:

-   -   measuring conditions: temperature range of about −80° C. to        about 50° C., frequency: 10 Hz, strain: 0.03%, heating rate: 2°        C./min    -   specimen size: 3 mm*60 mm, and    -   grip gap: 20 mm.        Young's Modulus, Modulus, and Elongation at Break Tests

Young's modulus, modulus at each of 100% and 300% of elongation, andelongation at break of the cleaning blades obtained in Examples 1 to 3and Comparative Examples 1 to 6 were measured by using a ShimadzuEZ-Test L Type Universal Testing Machine (UTM). Dumbbell no. 3 typespecimens were used, and the specimens were 2 mm thick. A measuringenvironment was at a temperature of 23° C. and humidity of 55% RH.

Herein, Young's modulus is a modulus value measured when the specimenswere elongated to 5% at a velocity of 10 mm/min. The modulus at anelongation of 100% and the modulus at an elongation of 300% weremeasured under a condition of elongating the specimen at a velocity of500 mm/min. The elongation at break is an elongation in which thespecimens break while being elongated at a velocity of 500 mm/min.

Rebound Resilience Test

Rebound resilience of the specimens were tested using a Lupke typeresilience tester (Model: VR-6500 Series) from SATRA-HAMPDEN accordingto JIS K 6255 standard under an environment having a temperature of23±2° C. and a humidity of 50±10% RH. Herein, six layers (12 mm totalthickness) of a circular specimen each having a diameter of 30 mm and athickness of 2 mm were laminated, the laminated product thereof was hitthree times using an impact bar, and a measured value of the reboundresilience of the circular specimen was recorded on a fourth hit. Thelocations of the impact bar were recorded in % after hitting thespecimen in which, when the impact bar returns to its initial location,the rebound resilience is recorded as 100%. Rebound resilience of thespecimens were also tested under a temperature condition of 10±2° C. anda temperature condition of 55±2° C.

Hardness Test

Hardness of specimens having a thickness of 2 mm were tested by using anIRHD rubber hardness tester from Bareiss GmbH after maintaining thespecimens for more than 8 hours in an environment having a temperatureof 23±2° C. and a humidity of 50±10% RH.

Test results described above were listed in Table 2 below.

TABLE 2 Blade Rebound abrasion resilience Modulus Cleaning resistanceYoung's (%) (MPa) Elongation performance (Crack) modulus @ @ @ @ @ atbreak @ @ @ @ @ Hardness (MPa) 10° C. 23° C. 55° C. 100% 300% (%) −5° C.N/N H/H N/N H/H E 1 79 9.8 10 32 54 5.7 30.2 331 ◯ ⊚ ⊚ >24K >16K E 2 725.4 21 33 62 3.6 21.5 336 ⊚ ⊚ ⊚ >24K >16K E 3 78 8.1 11 23 68 5.4 19.6415 ⊚ ⊚ ⊚ >24K >16K CE 1 83 11.6 27 46 73 5.1 10.9 450 ⊚ Δ X 12.4K  5.2K CE 2 78 13.1 13 35 64 5.1 10.0 373 ⊚ ◯ X >16K  2.6K CE 3 72 5.9 3349 62 5.9 17.8 336 ⊚ X X  7.6K  6.3K CE 4 75 7.84 11 21 66 4.6 22.3 305X ◯ ◯ >16K >16K CE 5 71 6.77 10 18 63 3.5 27.5 314 X ⊚ ⊚ >24K >16K CE 676 8.52 13 25 68 4.7 24.9 330 X ⊚ ◯ >24K >16K Response Factor ΔG *(MPa)/ΔT G * (MPa) @ −5° C. G * (MPa) @ 23° C. E 1 0.490 32.4 11.0 E 20.351 24.7 9.3 E 3 0.292 26.9 14.6 CE 1 0.199 16.6 7.2 CE 2 0.272 23.712.3 CE 3 0.098 14.2 9.2 CE 4 0.703 42.5 12.7 CE 5 0.540 34.2 13.2 CE 60.632 37.2 10.3 N/N: 23° C., 50~60% RH, H/H: 30° C., 80% RH

N/N: 23° C., 50-60% RH, H/H: 30° C., 80% RH

In reference to Table 2, the cleaning blades in Examples 1 to 3according to the present general inventive concept have similar valueswith respect to hardness, Young's modulus, rebound resilience, modulus,and elongation at break when compared to the cleaning blades inComparative Examples 1 to 6. However, by satisfying a shear modulusproperty such that the conditions (1), (2), and (3) are satisfied,cleaning performances in the N/N environment and abrasion resistance inthe H/H environment have been significantly improved.

The cleaning blade 3 according to the exemplary embodiments of thepresent general inventive concept has excellent cleaning performancewhen producing an image under a cryogenic environment and also hasexcellent abrasion resistance and durability in a high temperature andhigh humidity environment. In this regard, the electrophotographiccartridge 29 and the electrophotographic imaging apparatus 31 employingthe cleaning unit 21 having the cleaning blade 3 according to exemplaryembodiments of the present general inventive concept may provide highquality images for a long period of time even when theelectrophotographic cartridge 29 and the electrophotographic imagingapparatus 31 are used continuously at a high processing speed undervarious conditions. Hence, the cleaning blade 3 according to exemplaryembodiments of the present general inventive concept may achieve thefollowing effects:

(1) The cleaning blade 3 may efficiently remove a small diameterresidual toner, minimizing contamination of members of theelectrophotographic photoreceptor 11 and other developing apparatuses.Accordingly, high quality images may be provided for a long period oftime under various environmental conditions such as the cryogenicenvironment and the high temperature and high humidity environment.

(2) A cost of changing the cleaning blade 3, which is a consumableproduct, may be reduced as a lifespan of the cleaning blade 3 increases.

(3) A CR (Cleanerless) method may be selected, the method not employinga cleaner to clean a cleaning roller (CR).

Although a few embodiments of the present general inventive concept havebeen shown and described, it will be appreciated by those skilled in theart that changes may be made in these embodiments without departing fromthe principles and spirit of the general inventive concept, the scope ofwhich is defined in the appended claims and their equivalents.

What is claimed is:
 1. A cleaning blade to remove a residual tonerpresent on a surface of an electrophotographic photoreceptor, wherein avalue of the shear modulus of the cleaning blade over the change in atemperature range of about −5° C. to about 23° C. and a value of theshear modulus of the cleaning blade at a temperature of −5° C. obtainedfrom a dynamic viscoelasticity measurement measured as a function oftemperature in a temperature range of about −80° C. to about 50° C.under conditions of a frequency of 10 Hz, a heating rate of 2.0° C./min,and an initial strain rate of 0.03% satisfy the following conditions:0.292≦ΔG*(MPa)/ΔT(° C.)≦0.490,24.7≦G*(MPa)@−5° C.≦32.4, and wherein ΔG*(MPa)/ΔT(° C.) is a rate of thechange in the shear modulus value G* (unit: MPa) over the change in atemperature range ΔT(° C.) of about −5° C. to about 23° C., andG*(MPa)@−5° C. (unit: MPa) is the shear modulus value at the temperatureof −5° C.
 2. The cleaning blade of claim 1, wherein a value of the shearmodulus of the cleaning blade at a temperature of 23° C. furthersatisfies the following condition:9.3≦G*(MPa)@23° C.≦14.6, and wherein G*(MPa)@23° C. is the shear modulusvalue (unit: MPa) at the temperature of 23° C.
 3. The cleaning blade ofclaim 1, wherein the cleaning blade comprises a polyurethane.
 4. Acleaning unit to remove a residual toner present on a surface of anelectrophotographic photoreceptor, the unit comprising: a cleaningblade; and a supporting member to support the cleaning blade byattaching to at least one part of the cleaning blade; wherein thecleaning blade removes the residual toner present on the surface of theelectrophotographic photoreceptor, wherein a value of the shear modulusof the cleaning blade over the change in a temperature range of about−5° C. to about 23° C. and a value of the shear modulus of the cleaningblade at a temperature of −5° C. obtained from a dynamic viscoelasticitymeasurement measured as a function of temperature in a temperature rangeof about −80° C. to about 50° C. under conditions of a frequency of 10Hz, a heating rate of 2.0° C./min, and an initial strain rate of 0.03%satisfy the following conditions:0.292≦ΔG*(MPa)/ΔT(° C.)≦0.490,24.7≦G*(MPa)@−5° C.≦32.4, and wherein ΔG*(MPa)/ΔT(° C.) is a rate of thechange in the shear modulus value G* (unit: MPa) over the change in atemperature range ΔT(° C.) of about −5° C. to about 23° C., andG*(MPa)@−5° C. (unit: MPa) is the shear modulus value at the temperatureof −5° C.
 5. The cleaning unit of claim 4, wherein a value of the shearmodulus of the cleaning blade at a temperature of 23° C. furthersatisfies the following condition:9.3≦G*(MPa)@23° C.≦14.6, and wherein G*(MPa)@23° C. is the shear modulusvalue (unit: MPa) at the temperature of 23° C.
 6. The cleaning unit ofclaim 4, wherein the cleaning blade comprises a polyurethane.
 7. Anelectrophotographic cartridge comprising: an electrophotographicphotoreceptor; and a cleaning unit to remove a residual toner present ona surface of the electrophotographic photoreceptor after a visible imageformed thereon having been transferred onto an image-receiving member,wherein the electrophotographic cartridge supports theelectrophotographic photoreceptor and the cleaning unit and isattachable to and detachable from an electrophotographic imagingapparatus, wherein the cleaning unit comprises: a cleaning blade; and asupporting member to support the cleaning blade by attaching to at leastone part of the cleaning blade, wherein the cleaning blade removes theresidual toner present on the surface of the electrophotographicphotoreceptor, wherein a value of the shear modulus of the cleaningblade over the change in a temperature range of about −5° C. to about23° C. and a value of the shear modulus of the cleaning blade at atemperature of −5° C. obtained from a dynamic viscoelasticitymeasurement measured as a function of temperature in a temperature rangeof about −80° C. to about 50° C. under conditions of a frequency of 10Hz, a heating rate of 2.0° C./min, and an initial strain rate of 0.03%;satisfy the following conditions:0.292≦ΔG*(MPa)/ΔT(° C.)≦0.490,24.7≦G*(MPa)@−5° C.≦32.4, and wherein ΔG*(MPa)/ΔT(° C.) is a rate of thechange in the shear modulus value G* (unit: MPa) over the change in atemperature range ΔT(° C.) of about −5° C. to about 23° C., andG*(MPa)@−5° C. (unit: MPa) is the shear modulus value at the temperatureof −5° C.
 8. The electrophotographic cartridge of claim 7, wherein avalue of the shear modulus of the cleaning blade at a temperature of 23°C. further satisfies the following condition:9.3≦G*(MPa)@23° C.≦14.6, and wherein G*(MPa)@23° C. is the shear modulusvalue (unit: MPa) at the temperature of 23° C.
 9. Theelectrophotographic cartridge of claim 7, wherein the cleaning bladecomprises a polyurethane.